Footage of a loyalist band parading through Belfast City Hall while playing the Sash is being investigated by Belfast City Council.
Videos of the Scottish band – the Govan Protestant Boys from Glasgow – have been widely shared on social media after being captured over the weekend.
The band was at City Hall for an event to mark the centenary of the George Telford Memorial Orange Lodge on Saturday night.
Some of the councillors who approved the function have since condemned the display in the corridors of one of Belfast’s most iconic buildings.
They say a number of rules around the use of the shared space have been broken.
Among the criteria for event that functions are not permitted that are “potentially contentious or that involve significant reputation risks for the council”.
“It is damaging for the city to be projected in that way,” Sinn Féin councillor Ciaran Beattie said.
“That’s why it’s so unfortunate and that’s why we need to have this investigation – that’s why we need to get to the bottom of how it happened, why it happened, and to make sure events like this don’t happen in the future.”
Alliance councillor Emmet McDonough-Brown was on the committee that authorised the event and told UTV: “We gave them the use of the building –we didn’t authorise what we saw that night.
“I think everybody would agree that singing the Sash in Belfast City Hall is a contentious act and we think the organisers have questions to answer.”
SDLP councillor Carl Whyte added: “This was a band from Scotland – I would say to them: ‘You wouldn’t do that in Glasgow City Hall, so why do you think you could do that in Belfast City Hall?’”
No one from the DUP or UUP was available for comment.
The council would only say that it investigating the events of Saturday night.
George Telford Memorial Orange Lodge has confirmed that it held a private function at City Hall, and that it is aware of the videos of the band playing within the public area.
The lodge has pledged to fully co-operate with the investigation.